The effect of electrical stimulation of the sympathetic (splanchnic) nerve and parasympathetic (vagus) nerves on the hepatic glycogen synthase and phosphorylase systems in vivo in dog will be investigated. Effects on the enzyme systems will be correlated with measurements of hepatic cyclic AMP and cyclic GMP concentrations and plasma insulin and glucagon concentrations. Effects of nerve stimulation on glycogen synthase phosphatase and kinases enzyme systems will also be studied.